familyman;65838 wroteAdditionally - and I admit I'm not sure on this (someone please correct I'm wrong), but in 30 years of driving (one car for 7 years, another for 10 I think, maybe more), I've never replaced heater hoses. I've never HEARD of anyone in my family replacing them in their cars either. (Doesn't mean they didn't though.) Out of the 5 cars I've owned (for any good length of time) I think I've changed only two pairs of radiator hoses. One in a non-volvo because they had gone soft and gel-like, were suctioning-in on themselves - and because I was fitting a re-cored radiator at the same time. The one 240 I did it on was because I had no idea of knowing when or if the they had ever been done - plus I was replacing a weeping water pump at the time.
I recommend people at least do the heater hoses in the engine bay. Whilst they might superficially look alright you can only expect so much for 30 year old hoses. The ones in the interior are even more hidden and forgotten. Whilst pretty unusual I had a 2mm split open up on one when I hit redline during some spirited driving. Dumped several litres of coolant through my interior as I limped it home. Hose looked fine otherwise with no apparent reason for the failure ie no cuts, rotting, rubbing, etc.